1. Field of the Invention
The present invention relates to an intrusion monitoring arrangement or intrusion monitor (hereinafter simply monitor), which uses detecting means that enables the detection of intruding object in a 3-dimensional volume or space. More specifically, the invention relates to a monitor that enables detecting the position or actions of such an intruding object in a 3-dimensional volume or space (viz., an object to be monitored) with high degree of freedom.
2. Description of the Background Art
Conventionally, in the fields of FA (Factory Automation) and the like, so as to monitor a human body (viz., a person) intruding into a dangerous area, a monitor like a light curtain device, a laser scan type sensor or so has been employed.
A light curtain device has two posts arranged upright with an adequate distance (a light projecting post and a light receiving post). In the light projecting post, many light projectors are embedded with an appropriate intervals in the lengthwise direction thereof. In the same manner, in the light receiving post, many light receivers are embedded with an appropriate intervals in the lengthwise direction thereof. Between the light projecting post and the light receiving post, a light film (an optical curtain) is statically formed by many light beams connecting the light projectors and the light receivers. When this light film is blocked, an intruding object is detected via output from the light receivers.
In a laser scan type sensor, laser beam radiated from a laser light source is scanned linearly and repeatedly in a specified angle range, thereby a fan-shaped light film is dynamically formed. When this light film is blocked, an intruding object is detected via presence or absence of reflected light.
In the conventional monitors like the light curtain device and the laser scan type sensor and the like, mentioned above, the following problems have been pointed out by those skilled in the art.
(1) These monitors adopt detecting means that enables detecting an intruding object only in a 2-dimensional area (plane area), therefore, for example, in a situation where there are plural approaching routes to a dangerous object, in the case to monitor a human body approaching to such a dangerous object, it is required to install monitors in respective intruding routes, as a result, expenses for structuring a monitor system along with a new construction of a structure for installation thereof will increase, which has been a problem with the prior art. From the same reason, in the case of monitoring the degree of approach of an intruding object and forecasting the danger thereof, it is required to install monitors at a number of stages along the approaching route thereof, the expense of the monitor system will increase.
(2) Further, a light curtain normally forms a light film between 2 posts arranged upright, and is effective to an object that intrudes horizontally crossing this light film, while a light curtain is hardly effective to an object that comes in vertically along the light film. In addition, since the array pitch of light projectors and light receiver in posts is fixed, therefore, there is a limitation to the maximum size of an intruding object that can be detected, as a consequence, adjustment after installation lacks of degree of freedom, which has been another problem with the prior art.
(3) While, in a laser scan type sensor, normally a light film is applied horizontally close to a floor surface, therefore, a laser scan type sensor can detect feet of an intruder, but cannot detect hands or the like, as a result, it is hardly useful for the purpose of work safety. In addition, though there is a function to adjust a view angle, it is impossible to adjust response speed or resolution, which has been still another problem with the prior art.